supplied as pure colors, but tests have also been made to ascertain if 

 they were mixtures of more than one color. This was found to be 

 the case in a few instances. 



SOLUBILITY. 



The results given for solubility in Table I are only approximate and 

 were obtained by shaking an excess of the color with the various 

 solvents named, filtering, if necessary, and evaporating to dryness, in 

 order to determine the amount of color dissolved. The letters used to 

 express the varying degrees of solubility are explained in connection 

 with the table. Where the color of the solution is not given, it may 

 be assumed to be practically the same as that of the aqueous solution. 



The numbers in the last column of Table I are those of the corre- 

 sponding colors in Green's translation of the fourth German edition 

 of "A Systematic Survey of the Organic Coloring Matters," by 

 Schultz and Julius. 



EXTRACTION WITH IMMISCIBLE SOLVENTS. 



The determinations given in Table II were made as follows: 

 Twenty-five cubic centimeters of a 0.01 per cent solution of coal tar 

 color, or about 0.10 per cent solution of natural coloring matters, 

 were well shaken up with 25 cc of the -immiscible solvent in a sepa- 

 rating funnel. In the case of extraction with acetone the solution of 

 color was first saturated with common salt to render the acetone insol- 

 uble. After separation into layers, the amount of color extracted was 

 determined either by the relative depth of color in the two layers or 

 by taking equal volumes of each layer and ascertaining the propor- 

 tions by dyeing tests on plain or mordanted wool. The signs 0, > J 

 (more than half) , and < J (less than half) indicate the amount of color 

 extracted from the aqueous solution. The color given underneath the 

 above signs indicates the color of the immiscible solvent solution, 

 unless otherwise specified. From 5 to 10 drops of concentrated 

 hydrochloric acid or ammonium hydroxid (0.95 sp. gr.) were used to 

 make the solutions acid or alkaline. 



COLOR REACTIONS OF DYED FIBER. 



In the tests reported in Table III the wool was dyed with one-half 

 per cent of coal-tar color in every case; in the case of natural color- 

 ing matters the amount used was about ten times greater. A piece 

 of dyed zephyr yarn about 1 inch long was covered with 2 or 3 cc of 

 the reagent in a small porcelain dish. Unless the color of the reagent 

 became marked nothing is noted in the column marked " solution" in 

 the table. The color reactions were observed three or four minutes 

 after the addition of the reagent. The dyed fiber should be dry in 

 making these tests to prevent charring of the fiber by the strong acids. 



[Cir. 63] 



